Electric heater



J. L LAWRENCE ELECTRIC HEATER F'lled Aug. 15, 1922 April 7, 1925.

/NVENTOP JOSEPH L A WRENCE. BY

A TTOP/V VS.

Patented pr. 7, 1925..

UNITED STATES PATENT omer.;

v.Iosnrn L .,LAWRRNCR, or SAN IRaNcIysco, oaLIreRNre nssIeNoR To HERZOGELEG- VvTRIO @a ENGINEERING contraria?, or saN rRnNcIsco, CALIFORNIA, aoo RroRn- VTIoN `,or oaLIroRNIA.

ELECTRIC HEATER.

T 0 all 'whom 'it may concern:

Be it known that 1, JOSEPH L. LAWRENCE, a citizen ofthe United States,residing Lat the city Vand county oit San Francisco and State otGaliforniznhave invented new and usefulimprovements in Electric Heaters,ot which the kfollowing is a specification.

` This inventionrelates to electric heaters and especially to portableheaters such as employed in heating` individual rooms in residences,etc., as distinguished trom electric cookers, toasters and the like.

` Electric heaters, as generally designed, convert electric venergy intoheat by passing the current-or energy to a conductor having sufficientresistance to produce a sired 'or` predetermined temperature. yThe heatthus produced isin some instances projected by reflectors, 'and in'otherinstances by direct radiation and conduction, and again, by kaircirculation "by the heatpro- .duced is in most cases so localized thatthe effect oftheheater is only noticeable in the immediate vicinity. 1

The objectoiz the presentrinvention is to generally improve and simplifyelectric heaters, and especially that type inl which air circulationsought;l to provide large heating surfaces which will permit eiicientradiation and conduction, and to provide a novel arrangement of theheating elements with relation tov their supports and surroundingcasing, whereby efficient circulation and distribution of the heated airwill be obtained. Further objects willl lhereinaiter appear. A

The invention consists of the parts and the construction, combination`and arrangement of parts as' hereinafter more fully described andclaimed, having reference to the; accompanying drawings, in whieh Fig. 1is a central, vertical, longitudinal section '01 the heater.

Fig. 2 is a plan view of the same. f

Referring to the drawings in det-ail, A indicates a. base memberconsisting of a rectangular shaped plate 2 provided with supportinglegs'. Supported bythe base or plate 2 is a rectangular shaped exteriorsheet metal casing 4,' andv supported by the de-V Application `filedAugust 15, 1922. Serial No. 581,951.

casingin turn is a top plate 1B, .which coinprises of a rectangularshaped frame section i having a downwardly turnedflange 6 and a pair otcross hars 7. A pair otendopenenge 8 is thus formed inthe plate and acentral opening 9." rlhe v.side sections ot rvthe iranie are slightlyincreased in ,width as indicatedat 1U, and they cooperate with the crossbars 7 to itorm an inner frame to which is attached a rectangular shapedcasing v11; said casing being secured to the upper frame plate by meansof' a bottoni plate 12 and tie y rods 13. Mounted interior of the casingsection 11, and disposed concentric therewith and interspaced therefrom,is a pair oil inner casing sections 14e-and 1,5. These casingsaresupported entirely by the lower plate 12through means ot legsorupright bolts as indicated at 16. In other words direct contactbetween the lower ends ot the inner casing .sections 14 and 15 issnotmade with the bottom plate 12 as a spacing, such as shown at 17,isdesired to permit a slight circulation of airA for purposeshereinafter to be described. The upper end .ot the innermost casingindicated at 15 is flanged to form a frame as at 18, and this is coveredwith a wire mesh or screen 19; the-openings 8 at the respective endsthereof being ysimilarly covered with screens vas shown at.2().

rlphe heating elements employed are disposed within the inner casing 15as shown in Figs. 1 and 2. The-y are supported by .a central rod 21 andacro-ss arm 22. The

'elements employed may heef any suitable character, but consistpreferably of nichro-me wire wound Vabout lava spools or sleeves such asindicated at.23. The spools or sleeves carrying the windings` are hung'from the cross bar 22 by attaching the upper termina-ls of the windingthereto, andthe lowver ends or terminals of' the windings. are

the heating elements or the windinvs carried by the sleeves 23 in anysuitable manner, but these windings, together with the lava sleevessupporting the same, will within a very short time assume a red hottemperature. The heat produced is thrown ott' by radiation and the.surrounding air contained in the innermost 'casing 15 is thereby heatedand discharges upwardly through the screen 19. A slightly evacuatedcondition is produced in the lower end of the casing and an in rush ofair will thus take place from the lower chamber indicated at 30, whichis in communication with the atmosphere through the screen coveredopenings 8. 1n other words the moment circulation is started air willenter the screens in the direction of the arrows, see Fig. 1; it willthen pass through the lower chamber in the direction of the arrows, andwill finally discharge upwardly through the innermost casing 15 andescape through the screen 19.' Eiiicient circulation is in this mannermaintained and large volumes of heated air will constantly bedischarged. The air will not only be heated by radiation, but also bydirect contact with the windings and by passing through the interior ofthe spools or sleeves supporting the same as the lava spools assumesubstantially the same temperature as the windings supported thereby. Alarge heating surface is in this manner produced whereby direct contactwith the air is permitted, and whereby a large radiating surface is alsomaintained. This radiation will heat the exposed surfaces of theinnermost casing 15 and this will again heat the air by radiation andconduction. rhis heat should be restricted to the innermostcasing andthe heating clements proper as interference with efi'icient circulationof air would otherwise be produced. For instance if any of the heatshould be conducted or radiated to such an extent as to heat the casing11, then a Ynt upward current would be started in the ve"- ticalpassages communicating with the openings 8 and practically nocirculation of air would take place, but such heating of the casing 11is prevented due to the fact that the casings 11, 14 and 15 areinterspaeed and dead air spaces l!) and lll are formedbetwee'n the same.If the air in these spaces has any tendency to heat, a slight upwardcirculation will take place as air can enter these spaces through thelower annular opening 17. lThe screens indicated at 19 and 2O are merelyemployed for the purpose of excluding paper particles or to preventother articles from accidentally entering the casing of the heater, forinstance an object dropped through the opening 19 might do considerabledamage, particularly if one or another of the heating elements should beencountered, and it is for this reason that the openings employed arescreened.

ldfhile certain features of the present invention are more or lessspecifically illustrated, wish it. understood that various changes inform and proportion may be rei sorted to within the scope of theappended claims, similarly that the materials and finish of the severalparts employed may be such as the experience and judgment of themanufacturer may dictate or various uses may demand.

Having thus described my invention, what l claim and desire to secure byLetters Patent is 1. An electric heater, comprising a casing a. baseplate therefor and forming ay closure lfor the lower end thereof, a topplate carried by the casing having air inlet and discharge openingsformed therein, a casing attached to the top plate and interspaced withrelaL tion to the base plate, said casing communieating with thedischarge lopening at its upper end and with the inlet openings at itslower end, a` flange secured to the lower end of said last named easing,a second casing supported by the flange and interspaced with relationthereto to form a dead air space, and an electric heating elementdisposed within said second named casing.

2. An electric heater comprising a casing, a base plate therefor andforming a closure for the lower end thereof, a top plate carried by thecasing and having air inlet and discharge openings formed therein, a.casing attached to the top plate and interspaced with relation to thebase plate, said casing communicating with the discharge opening at itsupper end and with the inlet openings at its lower end, a flange securedto the lower end of said last named casing, a pair of interspacedcasings supported by the flange and interspaced therefrom, and anelectric heating element disposed within the innermost of said lastnamed casings.

3. An electric heater comprising a rectangular shaped casing, a baseplate forming a support and a closure for the lower end thereof, a pairof air inlet openings formed at each end of said plate and al eentrailair discharge opening also formed in said plate between the inletopenings, a rectangularl shaped casing supported by the top platecommunicating at its upper end with the air discharge opening and at itslower end with the air inlet openings, a rectangular shaped bottom plateattached to the lower end of said casing, a rectangular shaped casingsupported by said bottom plate and disposed within the second namedcasing and interspaced with relation thereto and an electric heatingclement disposed within the innermost of said last named casings.

4. In a heater of the character described the combination with theimieimost easing and the base plate, of a. vertically'disposed rodsupported by the base plate, a cifoss arm on the upper end of Saifi rod,pair of eieotrieal heating elements Suspended one from each end of saidarm, a pair of rods disposed n alignment with each of said heatingelements and Connected with said heating elements, and means for oi'minga eil."- cuit through the central rod and the last named rods to permitthe passage of a ouri'ent through the respective heating elements.

JOSEPH L. LAWRENCE.

